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What is EMF? How do we test for it?

Electromotive Force (EMF) is the measure of how much energy a source like a battery gives to the charges in a circuit. As with most things, this energy source is not 100% efficient, and has an associated int...
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Answered by Kieran M. • Physics tutor
4846 Views

Explain why a transformer only works with an alternating current and doesn't with a direct current.

A transformer is designed to step-up or step-down a voltage in a wire to make transferring electricity more efficient. To do this they contain two isolated coiled wires (of varied lengths depending on the tr...
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Answered by Brendan W. • Physics tutor
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Define Newtons law of Gravitation (in words or an equation).

Newtons law of gravitation can be described as: The force experienced by a body proportional to the product of the two masses the interaction is between, the gravitational constant 6.67x10 -11 , and the inve...
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Answered by Brendan W. • Physics tutor
4401 Views

Derive an expression to show that for satellites in a circular orbit T^2 ∝ r^3 where T is the period of orbit and r is the radius of the orbit.

This question is concerned with balancing forces. First, we must consider what forces are acting on the satellites. What is stopping the satellite from shooting off into space and what is preventing it from ...
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Answered by Charlie M. • Physics tutor
10409 Views

Draw a distance-time, speed-time, and acceleration-time graph for an object moving at a constant velocity of 5m/s for 10 seconds.

We know that the object is moving at 5m/s already telling us that the distance the object has travelled increases with time. Plotting distance on the y axis against time on the x axis we therefore expect a s...
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Answered by Hunain N. • Physics tutor
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